This invention relates to the co-texturization of reinforcing fibers and thermoplastic fibers and the resulting composite product.
It is common to include sound absorbing material in engine exhaust mufflers to dampen or attenuate the sound made by engine exhaust gases as they pass from the engine through the exhaust system to the atmosphere. One technological approach to this problem is disclosed in U.S. Pat. No. 4,569,471 to Ingemansson et al. The Ingemansson et al. patent describes a process and apparatus for feeding lengths of continuous glass fiber strands into a muffler outer shell. The apparatus includes a nozzle for expanding the fiber strands into a wool-like material before the fiber strands enter the outer shell. The nozzle disclosed in the Ingemansson et al. patent is capable of expanding strand material to a density of about 70 grams/liter or more. While such material is useful for its intended purpose, it has also been found that lower density materials of between about 30 grams/liter to about 60 grams/liter are desirable for many sound and thermal insulation applications.
U.S. Pat. No. 5,766,541 to Knutsson et al. discloses methods and apparatus for making preforms from continuous glass fiber strand material and binder material. Such preforms may be produced at a central location in order to reduce equipment costs and then the preforms may be shipped to other locations where they may be combined with muffler shells during subsequent assembly operations. The method disclosed in the Knutsson et al. patent comprises the steps of: (a) feeding continuous glass fiber strand material into a perforated mold to form a wool product in the mold; (b) feeding a binder in powdered form into the mold; (c) curing the binder to bond together portions of the strand material forming the compacted wool product such that a preform is formed having generally the shape of the mold; (d) opening the mold; and (e) removing the preform from the mold.
U.S. Pat. No. 5,976,453 to Nilsson et al. discloses a device and process for expanding strand material to densities as low as 30 grams/liter. Specifically, glass fiber roving is passed through a texturizing gun at feeding speeds of up to 400 meters/minute to 600 meters/minute simultaneously with pressurized gas at pressures up to 7.0 bars in order to produce a wool-like product suitable for use as acoustic and/or thermal insulation in automotive and industrial applications.
The present invention relates to a new method or process for producing a wool-type material of relatively low density including densities below 30 grams/liter which exhibit beneficial acoustic and/or thermal insulating properties suited for a multitude of automotive and industrial applications.
The present invention relates to a method of co-texturizing reinforcing fibers and thermoplastic fibers. The method comprises the steps of passing a continuous reinforcing fiber strand or roving through a texturizing gun, simultaneously passing a thermoplastic fiber strand or roving through the texturizing gun with the reinforcing fiber strand and injecting pressurized air into the texturizing gun concurrently with the reinforcing fiber and thermoplastic fiber strands. This method produces a co-texturized, composite wool-type product having densities ranging from about 20-200 grams/liter, preferably from about 20 grams/liter to less than about 30 grams/liter, and exhibiting beneficial acoustical and/or thermal insulating properties.
The reinforcing fiber strand may, for example, be any commercially available continuous glass fiber strand made from E-glass or S-glass fibers or a carbon fiber strand that is resistant to high levels of heat. The continuous thermoplastic fiber strand may be made from any appropriate thermoplastic fiber material known in the art including but not limited to polypropylene, polyethylene, polyethylene terephthalate, nylon and any mixtures thereof.
The reinforcing fiber strand and the thermoplastic fiber strand are passed or fed through the texturizing gun at a rate of between approximately 300-600 meters/minutes and more typically about 400 meters/minute. The pressurized air may be injected into the texturizing gun at pressures ranging from about 1.0-7.0 bars and more typically about 3.0 bars. Still further, the reinforcing fiber strand and thermoplastic fiber strand may be passed through the texturizing gun in amounts so as to produce a co-texturized composite product of from about 1 to 99% and more typically from about 20 to about 85% by weight reinforcing fiber.
The co-texturized product may, for example, be blown from the texturizing gun directly into an assembled product or into a mold. In the alternative, the method may include the step of placing the co-texturized reinforcing and thermoplastic fiber material discharged from the texturizing gun into a bag. Typically, the bag is constructed from a thermoplastic material such as but not limited to polypropylene, polyethylene, polyethylene terephthalate, nylon and any mixtures thereof The bag and the co-texturized reinforcing and thermoplastic fiber contents thereof may then be subsequently used as a load for a molding machine and molded under heat and pressure into a desired shape for any appropriate application.
In accordance with yet another aspect of the present invention, a cotexturized fiber material is provided. That co-texturized fiber material comprises between 1-99% by weight reinforcing fiber material and 1-99% by weight thermoplastic fiber material and more typically between about 20-85% by weight reinforcing fiber material and 15-80% by weight thermoplastic fiber material. The co-texturized material has an overall density of from about 20 grams/liter to about 200 grams/liter and preferably from about 20 grams/liter to less than about 30 grams/liter. The continuous reinforcing fiber material may be selected from a group consisting of glass fibers (e.g. E-glass fibers, S-glass fibers), carbon fibers and any mixtures thereof. The thermoplastic fibers may be selected from a group of materials consisting of polypropylene, polyethylene, polyethylene terephthalate, nylon and any mixtures thereof. It should be appreciated, however, that the specific continuous reinforcing fibers and thermoplastic fiber materials listed are only being presented for purposes of illustration and are not to be considered as restrictive.
Still other benefits and advantages of the present invention will become apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawing and descriptions will be regarded as illustrative in nature and not as restrictive.